Pregnant Drinking Increases Child's Risk of Alcohol Disorder

Action Points

Inform interested patients that alcohol intake during pregnancy, especially in the first six months, increases the risk that their child will later develop an alcohol disorder such as alcohol dependency.

Caution patients of child-bearing age that many authorities believe no amount of alcohol consumption is safe during pregnancy.

HERSTON, Australia, Sept. 4 -- Children of mothers who drink during pregnancy have a greater risk of developing alcohol problems as they grow up, according to Australian researchers.

This is particularly so for mothers who drink during the first two trimesters, reported Rosa Alati, Ph.D., of the University of Queensland here, and colleagues, in the September issue of Archives of General Psychiatry.

Children exposed to at least three glasses of alcohol in utero per given occasion during the first two trimesters were about three times more likely to develop early- (ages 13 to 17) or late-onset (ages 18 to 21) alcohol disorders than those who were not exposed in utero, even after adjustment for a full range of confounding factors, the investigators found.

Exposure to the same alcohol levels during the third trimester increased the adjusted odds ratio of early- and late-onset alcohol disorders somewhat as well (1.35, 95% confidence interval 0.69 to 2.63, and 1.67, 95% CI 0.84 to 3.31, respectively).

"Our findings suggest that, compared with less frequent exposure, in utero exposure to three or more glasses consumed as frequently as a few times a month is associated with double the risk of both early- and late-onset alcohol disorders in youth," they wrote.

Since exposure in early pregnancy when the central nervous system is developing was a stronger predictor than exposure in late pregnancy, the results "provide support for a biological origin of adult alcohol disorders," wrote the authors.

While genetic predisposition may be a confounding factor, the magnitude of the associations between prenatal alcohol exposure and later alcohol disorders remained the same in a model that excluded the 216 cases in which the mother reported that the father or sibling had alcohol problems.

Those who were born to mothers who drank during both early and late pregnancy periods had an adjusted odds ratio of 2.49 (95% CI 1.06 to 5.85) for early-onset alcohol disorders and of 2.43 (0.91 to 6.44) for late-onset disorders.

Children of mothers that reported drinking at least three glasses of alcohol on occasion but not during pregnancy had no elevated risk of early onset alcohol disorders and a 1.52 fold increase in late onset disorders (95% CI 1.12 to 2.07, adjusted model). The authors said this "reflects a possible contribution of genetic or childhood and adolescence environmental exposures, or both, to alcohol use."

The investigators analyzed data from an Australian longitudinal cohort study designed specifically to look at antenatal alcohol consumption. Of the 2,138 mothers with complete alcohol intake information, 9.4% had consumed three or more glasses of alcohol during pregnancy (3.8% early pregnancy only, 3.9% late pregnancy only, 1.7% both).

At the 21 year follow-up, a quarter of the children born in the study met DSM IV criteria for alcohol abuse disorders, 13.0% with early onset before age 18 and 12.0% from 18 to 21, while 6.1% of these also met criteria for alcohol dependence.

Mothers who drank alcohol in pregnancy were more likely to be smokers, unmarried during pregnancy, and to have children with "externalizing" symptoms at age 14.

In fact, "maternal smoking during pregnancy attenuated the association between in utero alcohol exposure and alcohol disorders in youth but did not confound it," the researchers wrote, "suggesting that a common mechanism may underlie the effect of both exposures on the brain's natural reward circuitry."

Other human and animal studies have shown this same link but not examined the timing of the prenatal insult.

In 2005, the U.S. Surgeon General warned pregnant women and women who may become pregnant to abstain from alcohol consumption, which updated the 1981 advisory suggesting that pregnant women limit the amount of alcohol they drink.

Reviewed by
Rubeen K Israni, MD, Fellow, Renal-Electrolyte and Hypertension Division, University of Pennsylvania School of Medicine